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July
20, 2009: One one-thousand, 2 one-thousand, 3
one-thousand, 4 one-thousand...
Continue
counting and don't stop until you reach 399 one-thousand.
Did
that feel like a long time? Six minutes and 39 seconds to
be exact. That's the duration of this week's total solar eclipse--the
longest of the 21st century.
The
event begins at the crack of dawn on Wednesday, July 22nd,
in the Gulf of Khambhat just east of India. Morning fishermen
will experience a sunrise like nothing they've ever seen before.
Rising out of the waves in place of the usual sun will be
an inky-black hole surrounded by pale streamers splayed across
the sky. Sea birds will stop squawking, unsure if the day
is beginning or not, as a strange shadow pushes back the dawn
and stirs up a breeze of unaccustomed chill.
Right:
A totally eclipsed sunrise in Antarctica. Credit and Copyright:
Fred Bruenjes of moonglow.net. [more]
Most
solar eclipses produce this sort of surreal experience for
a few minutes at most. The eclipse of July 22, 2009, however,
will last as long as 6 minutes and 39 seconds in some places,
not far short of the 7 and a half minute theoretical maximum.
It won't be surpassed in duration until the eclipse of June
13, 2132.
From
the Gulf of Khambhat, the Moon's shadow will race east across
India, China, and the Ryukyu Islands of Japan. Click on the
image to launch an animated map:
Above:
Clicking on this image will launch an animated global
map of the July 22nd eclipse. Regional animations of India
and China
are also available. Credit: Larry Koehn of ShadowAndSubstance.com.
The
path of totality cuts across many large cities. The shadow
will linger over Shanghai, the largest city in China, for
six full minutes, giving 20 million residents a lengthy and
stunning view of the sun's ghostly corona. Other large cities
in the path of totality include Surat, Vadodara, Bhopal, Varanasi,
Chengdu, Chongqing, Wuhan, Hefei, Hangzhou. The population
of each numbers in the millions, making this possibly the
best-observed solar eclipse in human history.
The
eclipse is extra-long because of a lucky coincidence, made possible
by the elliptical shape of planetary orbits. On July 22nd, Earth
happens to be near its farthest point from the sun. A small
sun means the Moon can cover it longer. At the same time, the
Moon will be near its closest point to Earth. A large Moon covers
the sun longer, lengthening the eclipse even more.
The
leisurely pace of the eclipse could have a transformative
effect on witnesses. Total eclipses have been known to turn
ordinary folk into life-long "eclipse-chasers" willing
to spend thousands of dollars and travel tens of thousands
of miles to feel the Moon's cool shadow and behold the sun's
pale atmosphere just one more time. A few extra minutes
of wonder will intensify this effect to an unknown degree.
Live
webcasts of the eclipse--not the next best thing
to being there, but the only substitute available to many
readers--may be found at the
website of the San Francisco Exploratorium. Broadcasts
commence at 9 p.m. EDT on July 21st (0100 UT on July 22nd).
Let
the counting begin.
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Author: Dr.
Tony Phillips | Credit: Science@NASA
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